1. Field of the Invention
The present invention relates to a refrigerant compressor used for a refrigerating machine.
2. Discussion of Background
FIG. 8 is a cross-sectional view in a longitudinal direction of a scroll compressor shown in Japanese Patent Application JP9-268579 as a background art. Numerical reference 1 designates a fixed scroll, of which outer periphery is fastened by bolts (not shown) to a guide frame 15. A spiral turbine 1b is formed in one surface (a lower side in FIG. 8) of a seat 1a, and a pair of a Oldham's coupling grooves are formed to be substantially linear in an outer periphery of the seat, with which Oldham's coupling groove 1c a pair of fixed projections 9c of an Oldham's coupling 9 are engaged so as to be reciprocally slidable. A suction tube 10a is press-fitted to a hermetically sealed vessel by penetrating from a side of the fixed scroll 1 (a right side in FIG. 8).
Numerical reference 2 designates a rotating scroll, on one surface of a seat 2a (an upper side in FIG. 8) of which a spiral turbine 2b having substantially the same shape as that of the spiral turbine 1b of the fixed scroll 1 is formed. On a central portion of an opposite surface (a lower side in FIG. 8) to that of the spiral turbine 2b of the seal 2a, a boss 2f having a hollow cylindrical shape is formed, and on an inner side surface of the boss 2f, a bearing 2c is formed. Further, on an outer periphery in the same surface as that of the boss 2f, a thrust face 2d which is slidably in contact with a thrust bearing 3a of a compliant frame 3 is formed. In an outer periphery of the seal 2a of the rotating scroll 2, a pair of Oldham's coupling groove 2e are formed to be substantially linear, which has a phase difference of about 90.degree. from the Oldham's coupling groove 1c of the fixed scroll, to which Oldham's coupling groove 2e a pair of rotating projections 9a of the Oldham's coupling 9 are engaged reciprocally slidable.
In a central portion of the compliant frame 3, a main bearing 3c and an auxiliary main bearing 3h, both for holding a main shaft 4 rotatably driven by a motor in the direction of its radius are formed. Although an outer periphery 15g of the guide frame 15 is fixed to the hermetically sealed vessel by an interference shrink fit, a welding or the like, a flow path for introducing a refrigerant gas having a high pressure discharged from a discharge port 1f of the fixed scroll 1 from the guide frame 15 to a discharge tube 10b provided on the side of motor (lower side in FIG. 8) is maintained. An upper bore surface 15a is formed on the side of fixed scroll in an inner side surface of the guide frame 15 (upper side in FIG. 8) and fitted and engaged with an upper cylindrical surface 3d formed in an outer periphery surface of the compliant frame 3. On the other hand, a lower bore surface 15b is formed on the side of motor in an inner side surface of the guide frame 15 (lower side in FIG. 8) and fitted and engaged with a lower cylindrical surface 3e formed in an outer peripheral surface of the compliant frame 3. In an inner side surface of the guide frame 15, two sealing grooves for accommodating a sealing material are formed, and an upper seal 16a and a lower seal 16b are fitted and engaged with these sealing grooves. A space 15f formed among these two seals, the inner side surface of the guide frame 15 and the outer side surface of the compliant frame 3 is connected to a space around the boss 2h through a pressure equalizing aperture 3i formed in the compliant frame 3. The upper seal 16a and the lower seal 16b are not necessarily indispensable and can be omitted if sealing is possible in a micro-clearance among engaging portions. A space around the outer periphery of the seat 2i, which is in the outer peripheral side of the thrust bearing 3a surrounded by the seat 2a of the rotating scroll and the compliant frame 3 in the vertical directions, is connected to a suction chamber 1g in the vicinity of an end of the spiral turbine to have an atmosphere of suction gas.
In an end of the main shaft 4 on the side of rotating scroll (upper side in FIG. 8), an orbit shaft body 4b which is rotatably engaged with the bearing 2 of the rotating scroll 2 is formed. To the lower side of the main shaft, a main shaft balancer 4e is fixed by an interference shrinkage fit, and a main shaft body 4c which is rotatably engaged with the main bearing 3c and the auxiliary main bearing 3h both of the compliant frame 3 is formed beneath the main shaft balancer. On the other end of the main shaft, a subshaft body 4d rotatably engaged with a subbearing 6a of a subframe 6 is formed. Between the subshaft body 4d and the above-mentioned main shaft body 4c, a rotor of motor 8 is fixed by an interference shrinkage fit. An upper balancer 8a is formed on an upper end of the rotor 8, and a lower balancer 8b is fastened to a lower end of the rotor, whereby a static balance and a dynamic balance are maintained by the above-mentioned main shaft balancer 4e and these three balancers. An oil pipe 4f is press-fitted to a lower end of the main shaft 4 for sucking up a refrigerating oil 10e accumulated in a bottom of the hermetically sealed vessel 10. A glass terminal 10f is attached to a side surface of the hermetically sealed vessel 10, to which glass terminal a lead wire from a stator of motor is connected.
Standard operation of the conventional scroll compressor will be described. In normal operation, because an area of the hermetically sealed vessel 10d has a high pressure under an atmosphere of discharge gas, the refrigerating oil 10e in the bottom of the hermetically sealed vessel 10 is introduced from a high-pressure lubrication hole 4g formed in the main shaft 4 by penetrating in the axial direction to a space in the boss 2g. This high-pressure oil is depressurized by the bearing 2c so as to have an intermediate pressure and flows toward the space around the boss 2h. The refrigerating oil having an intermediate pressure flows through the pressure equalizing aperture 3i to the space 15f and is released to the space around the outer periphery of the seat 2i having a low pressure through an intermediate pressure adjusting valve or the like. Although downward force as much as the sum of force caused by the intermediate pressure in the space around boss 2h and a pressure from the rotating scroll 2 through the thrust bearing 3a effects on the compliant frame 3, upward force as much as the sum of force caused by the intermediate pressure in the space 15f and a force caused by the high pressure effecting on a portion exposed to the atmosphere of high pressure in the lower end surface produces force larger than the downward force in the normal operation. Accordingly, in the compliant frame 3, the upper cylindrical surface 3d is guided by the upper bore surface 15a of the guide frame and the lower cylindrical surface 3e is guided by the lower bore surface 15b of the guide frame 15, whereby the compliant frame 3 floats on the side of the fixed scroll in the upward direction in FIG. 8. Also the rotating scroll 2 pushed to the compliant frame 3 through the trust bearing 3a floats in the upward direction, wherein tops and bottom of the rotating scroll 2 are slidably in contact with bottom and tops of the fixed scroll 1 respectively.
At a time of starting up and liquid compression, a load by gas in the thrust direction effecting on the rotating scroll 2 is increased to strongly push down the compliant frame 3 on the reverse side of the fixed scroll through the rotating scroll 2 and the thrust bearing 3a. Therefore, a relatively large gap is produced between the tops and the bottom of the rotating scroll 2 and the bottom and the tops of the fixed scroll 1 so as to be able to avoid an abnormal pressure increase in a compression chamber. The amount of relief is determined by a distance between a contact face 3q of the compliant frame 3 and a contact face 15h of the guide frame 15. Incidentally, although a part of or all of overturning moment generated in the rotating scroll 2 is transmitted through the thrust bearing 3a, resultant force of a load received from the main shaft bearing 3c and a reaction to the load, namely coupled force of reaction force received from the guide frame 15 through the upper cylindrical surface 3d and reaction force received from the guide frame 15 through the lower cylindrical surface 3e, acts to compensate the overturning moment, whereby excellent stability in follow-up operation and also in relief operation is obtainable.
In the conventional scroll compressor of which compliant frame was movable in the axial direction by maintaining its own balance in terms of the moment, i.e. so-called compliant frame type scroll compressor of the background art, the intermediate pressure in the space around boss 2h leaked to the space around outer periphery of seat 2i when the rotating scroll 2 flapped on the thrust bearing 3a of the compliant frame 3 by a tiny outer disturbance such as a variation of a condition of operating pressure and suction of liquid refrigerant. Consequently, the intermediate pressure in the space 15f leaked to the space around outer periphery of seat 2i having an atmosphere of low pressure through the pressure equalizing aperture 3i. Accordingly, force for lifting the compliant frame 3 up on the side of the fixed scroll (upward direction in FIG. 8) was decreased to thereby relieve the compliant frame 3 on the reverse side of the fixed scroll (downward direction in FIG. 8) along with the rotating scroll 2. In other words, there was unstability that the rotating scroll 2 was easily relieved by a tiny outer disturbance.
Further, in the conventional scroll compressor, a degree of freedom in setting a working area of the space 15f, i.e. an area having the intermediate pressure, which was a major factor of lifting up the compliant frame 3 on the side of the fixed scroll (upward direction in FIG. 8), was less because it should have be restricted by a working area of the space around boss 2h, i.e. the same space having the intermediate pressure as that of the space.
Further, in the conventional scroll compressor, the intermediate pressure in the space 15f, which was a major factor of lifting the compliant frame 3 up on the direction of fixed scroll (upward direction in FIG. 8) just after starting up, was generated such that an inner pressure of the hermetically sealed vessel 10 was increased and the refrigerating oil 10e having a high pressure was choked by the bearing and flows into the space 15f. Therefore, there was a time lag until the intermediate pressure in the space 15f starts to rise. Accordingly, there was a problem that it took a time until the compliant frame 3 floated for the normal operation, in other words, a considerable amount of time was necessary for starting up.
Further, in the conventional scroll compressor, there were problems that the spiral turbines 1b and 2b may have been destroyed and that the bearing 2c and the main bearing 3c are seized by an excessive load as a result of an abnormal pressure rise in the compression chamber, formed by the spiral turbine 1b of the fixed scroll 1 and the spiral turbine 2b of the rotating scroll 2, caused by a liquid compression when an amount of play in the axial direction of the compliant frame 3 was small enough to allow a liquid refrigerant to suck in a running state.
Further, in the conventional scroll compressor, there were problems that an extremely long period was necessary to realize normal operation by making the compliant frame 3 float or that starting-up was impossible at worst because, when the amount of play in the axial direction of the compliant frame 3 was large, the compliant frame 3 was maximally relieved at the time of starting up so that the rotating scroll 2 was apart from the fixed scroll 1 to the maximum extent in the axial direction; the rotating scroll 2 arbitrarily rotates with effecting less compressing operation; and therefore the inner pressure of the hermetically sealed vessel is scarcely increased.